You will see a contract that says "Employee to start July 1st. Employment is at will. Either party may terminate with two weeks notice". You will think the first is the most important. The student might find the last clause most important.
When the student calls in January to give several months notice that they wont be accepting the offer, you have a fucking tantrum and say that the student is unethical and unprofessional. You will imagine in your head that the contract meant "Notice cannot be given until after employment has commenced". That this clause is not there will not bother you. Thats what you thought it meant, and by golly you are a man of your word, whereas this student is clearly a liar and a cheat, weaseling out of a contract with word tricks.
I have met many moral absolutists, and their primary attribute is that everyone else is a liar and a cheat. They then use that excuse to break any deal they chose.
"I have met many moral absolutists, and their primary attribute is that everyone else is a liar and a cheat."
In my experience, people who have very low opinions of everyone else (and those include the absolutists on both sides of this debate) are usually the least trustworthy people I have met.
No, they accepted an offer of employment, with a start date. The employer has every reason to believe they've done so in good faith.
If, in fact, they were insincere in their acceptance, that's both unethical and unprofessional.